The present disclosure broadly relates to the art of spring devices and, more particularly, to a gas spring and gas damper assembly that includes a gas spring used in combination with a gas damper, as well as a vehicle suspension system and a method of operating such a gas spring and gas damper assembly.
Suspension systems, such as may be used in connection with motorized vehicles, for example, typically include one or more spring elements for accommodating forces and loads associated with the operation and use of the corresponding system or device (e.g., a motorized vehicle). In such applications it is often considered desirable to select spring elements that have the lowest suitable spring rate, as this can favorably influence certain performance characteristics, such as vehicle ride quality and comfort, for example. That is, it is well understood in the art that the use of a spring element having a higher spring rate (i.e. a stiffer spring) will transmit a greater magnitude of inputs (e.g., road inputs) to the sprung mass and that, in some applications, this could undesirably affect the sprung mass, such as, for example, by resulting in a rougher, less-comfortable ride of a vehicle. Whereas, the use of spring elements having lower spring rates (i.e., softer, more-compliant springs) will transmit a lesser amount of the inputs to the sprung mass. In many cases, this will be considered a desirable affect on the sprung mass, such as by providing a more comfortable ride, for example.
Such suspension systems also commonly include one or more dampers or damping elements that are operative to dissipate undesired inputs and movements of the sprung mass, such as road inputs occurring under dynamic operation of a vehicle, for example. Typically, such dampers are liquid filled and operatively connected between a sprung and unsprung mass, such as between a body and axle of a vehicle, for example. In other arrangements, however, the damping element can be of a type and kind that utilizes gaseous fluid rather than liquid as the working medium. In such known constructions, the gas damper portion permits gas flow between two or more volumes of pressurized gas, such as through one or more orifices, as shown, for example, in U.S. Patent Application Publication No. 2004/0124571, or through one or more valve ports, as shown, for example, in U.S. Patent Application Publication No. 2003/0173723. Generally, there is some resistance to the movement of pressurized gas through these passages or ports, and this resistance acts to dissipate energy associated with the gas spring portion and thereby provide some measure of damping.
One difficulty with known gas spring and gas damper assemblies involves balancing spring rate with damping performance. It is generally understood that increased damping performance can be achieved through the use of increased differential pressure between the gas chambers of the gas damper. In some cases, this can be achieved by operating a gas damper at an increased internal gas pressure. However, this increased gas pressure can, in some cases, have an undesirable affect on the spring rate of the gas spring, such as by undesirably increasing the spring rate in applications in which a lower spring rate is desired, for example.
Accordingly, it is desired to develop a gas spring and gas damper assembly as well as a suspension system and method using the same that overcome the foregoing and other difficulties associated with known constructions.